Wednesday, November 12, 2014
A contractor with the Port of Hood River will begin inspections this week to try and figure out why the lift span of the Hood River Bridge isn’t setting properly in the down position.
The port has signed a $60,000 contract with Portland engineering firm HDR to perform inspection work and determine why a ¾-inch gap exists between the bottom of the lift span and the bearings — points of contact between the bridge piers and the 262-foot-long lift span — and how to fix it.
According to the port, the gap is located at the northwest corner of the lift span in the center of the bridge — a component that is raised and lowered on the rare instance that a passing ship is too tall to make it under the 67-foot clearance, give or take, depending on the water level of the Bonneville Pool.
Port Executive Director Michael McElwee said the issue with the bridge is not an imminent threat to motorist safety and that the repair was “about careful, prudent, active management of the movable lift span,” which he classified as “arguably, the most important portion” of the Hood River Bridge.
“It’s not an immediate safety issue, but it’s something that needs to be addressed,” he said of the gap, adding that the port wants “to be in a preventive mode, not a reactive mode.”
David McCurry, project lead at HDR who previously worked as the bridge engineer, likened the lift span issue to that of a wobbly four-legged stool or table, where one of the legs won’t quite touch the floor.
McCurry echoed McElwee’s sentiment that the issue was not of immediate concern. He said the gap is minor enough that it isn’t noticeable when traveling over the bridge in a vehicle and noted that there’s “enough flexibility there that the system allows (the lift span) to set down anyway.”
The problem was detailed in a report by another bridge contractor, HNTB, after an inspection conducted in February this year discovered other issues. One notable malfunction was that the traffic barrier gates — which prevent vehicles from driving forward after the lift span has been raised — did not fully lower. McElwee said the arms “required immediate attention and are fixed now.”
According to a port memo, though the gap itself is not particularly large, the discovery of the lift span issue was “a very important finding because incorrect setting places stress on other (bridge) components, could be causing further damage to those components and could, over time, render the span non-operational.”
McElwee said HNTB identified a number of issues that could be the source of the problem, but did not find the actual cause. McElwee said one issue could be the steel cables that raise and lower the span have stretched and lost tension, although he thought it unlikely the components needed to be replaced.
“We think it’s going to be pretty small,” he said of the repairs, “but if they have to replace the cables it will be a pretty significant project. At this point the engineers don’t think that’s going to be necessary.”
HNTB gave a wide range of $50,000 to $500,000 for the repair costs, as the specific problem hadn’t been identified. McElwee noted that what the port is “carrying in our budget to respond to any repairs in the lift span is $350,000.”
The port’s contract with HDR requires the engineering firm to identify the specific problem affecting the lift span, create a list of repair recommendations and estimates, and produce a maintenance manual and a data set to help with the long-term preservation of the lift span.
According to the draft work plan proposed by HDR, inspection of the bridge will take place Friday, weather permitting (which it may not permit, see cold weather story on page A1), and may require some traffic control so as to allow equipment onto the bridge.
On Monday, Nov. 17, the port plans to continue the inspection process, which will entail four to six full lifts of the main span throughout the day. The first lift is not scheduled to occur until after 9 a.m. and each lift takes around 15 minutes to complete.
The port advises those who use the bridge for commuting to allow for extra crossing time that Monday. Those with questions can call the port at 541-386-1645.